The present invention relates generally to fluid infusion systems, and more particularly to an improved apparatus for detecting the formation of bubbles in such systems.
The infusion of fluids such as parenteral fluids and blood into the human body is usually accomplished by means of an administration set and metering apparatus which controls the rate of flow of fluid through the set. Peristaltic-type pumps, which function by repetitively compressing and expanding a section of tubing, have proven particularly attractive for use in such metering apparatus since they do not introduce the possibility of leakage or contamination into the system, while providing positive control of fluid flow through the system. One form of metering apparatus employing a peristaltic-type pump is described in U.S. Pat. No. 4,155,362, which issued to Thurman S. Jess on May 22, 1979, and is assigned to the present assignee. A successful commercial embodiment of this apparatus is currently marketed as the Travenol Model 2M8014 infusion pump by Baxter Travenol Laboratories, Inc., of Deerfield, Ill.
One problem which arises with the use of fluid infusion sets is that dissolved gases in the liquid being infused may be released as bubbles as the liquid is subjected to pressure and/or temperature changes as it passes through the pump of the metering apparatus. These bubbles may coalesce and form larger bubbles or pockets of gas which may be infused along with the liquid into the body, an occurence which may be harmful or even fatal to the patient under certain circumstances.
To prevent gas from being infused it has become common practice to locate a bubble detector downline of the metering apparatus pump to automatically stop the apparatus should gas bubbles be detected. Such detectors typically employ a light source and a light detector positioned on opposite sides of the administration set tubing to monitor the level of light transmitted through the tubing. Operation of the metering apparatus is interrupted and an alarm is sounded when the transmitted light level falls below a predetermined level.
One preferred form of bubble detector utilizes the focusing or lens effect of the fluid in the lumen of the tubing to enhance the difference in light transmission levels through the tubing between fluid and no fluid conditions. The present invention is directed to an improvement in such systems whereby improved responsiveness to the absence of fluid in the tubing is achieved.
Accordingly, it is a general object of the present invention to provide a new and improved bubble detector.
It is another object of the present invention to provide a new and improved bubble detector having improved responsiveness to the absence of fluid in the tubing being monitored.
It is a further object of the present invention to provide a bubble detector wherein the lens effect of fluid within the lumen of the tubing being monitored is utilized to detect with improved responsiveness the absence of fluid within the tubing.